Bore finishing tool



Feb. 24, 1959 E. A. THOMPSON BORE FINISHING TOOL Filed Dec. 7, 1955 l l I INVEN TOR.

EA 2L A. 7i/0MP50N Arne/vars.

the arbor and parallel thereto.

United States Patent "ice 2,874,452 Bonn FINISHING TOOL EarlA. Thompson, 'Ferndale, jMich.

Application December 7, 1955, Serial No. 551,572

4 Claims. (Cl. 29-90) This invention relates to an apparatus for finishing cylindrical bores in work pieces and has to do more particularly with a tool adapted to provide the bore of a work piece with ahardened, extremely smooth and very accurate cylindrical surface.

In the drawings:

Fig. 1 is a side elevational view partly in section of the apparatus according to the present invention.

Fig. 2 is a sectional view along the lines 2-2 in Fig. 3 and showing the expanding arbor at the front end of the apparatus illustrated in Fig. vl andfurther showing the work piece arranged thereon.

Fig. 3 is a sectional view along'the lines 3-3inFig. 2.

Fig. 4 -is a' detail sectional view of the check valve employed in the arrangement shown in Fig. 1.

Referring particularly to Fig. 2, ,the tool proper isin the nature of an expanding arbor generally designated which includes a hollow spindle 12; Spindle .12'is fashioned as atubular member having a side wall .14 of uniform thickness and an 'end wall 16. The outer surface of side wall 14 is accurately ground to true cylindrical shape. Around the outer surface of side wall 14, there are arranged finishing rollers 18 and guide pins As isseen more clearly in Fig. 3, .it will be observed that a guide pin 29 is arranged between successivepairs of finishing rollers 18. These rollers and guidepins are supported around the outer surface of the sidewall 14 by a front retainer 22 and a rear retainer 24. The front end wall 16 of member 12 is fashioned with a reduced threaded portion 26, and the front retainer 22 is in the form of a cap having a threaded end 28 engaged with the threaded end 26 of member 12. Retainer 22 has a cylindrical wall portion 28 telescoped over the outer surface of wall 14 and at the free end thereof is provided with an annular flange 30 fashioned with a conically-shaped race 32. Rear retainer 24 has a slip fit on spindle 12 and is provided with a comically-shaped race 34 at the end thereof. Retainers 22 and 24 are spaced axially apart on spindle 12 so that the races 32 and 34 engage the conicallyshaped opposite ends 36 of the finishing rollers 18 and maintain these rollers in contact with the outer surface of the side wall 14 of spindle 12. At circumferentially spaced points corresponding to the spacing of rollers 20, the rear retainer 24 is fashioned With sockets 38 in which the rear ends of the guide pins 20 are press fitted. Thus, as is seen in Fig. 3,'guide pins 20 maintain the finishing rollers 18 in true axial alignment with the axis of spindle 12. The retainers22 and 24 with pins 20 thus form a cage for constraining the rollers 18 to positions adjacent The bore of retainer 24 adjacent the race 34 is preferably undercut as shown at 40. The bore of the cylindrical wall portion 28 of retainer 22 may be similarly undercut, if desired; but since retainer 22 is of relatively light section as compared with retainer 24, undercutting of the bore of retainer 22 has not been found to be necessary. It will be observed that the annular flange '30 of retainer 22 has an outer diamsubjecting the interiorthereof to' an expanding pressure Patented Feb. 24, 1959 eter less than the circle formed by the radially outermost surfaces of rollers 18, thus enabling a workpiece such as shown at42 to he slipped over the end of the arbor 10 with its bore 44 contacting rollers 18.

With this arrangement, it will be observed that if spindle 12 is rotated and bore 46 thereof is subjected to a relatively high internal pressure, the side wall 14, or atleast the portion of side wall 14 between retainers 22 and 24, will be generally uniformly expanded to rotate rollers 18 by bringing them into substantial pressure contact with the bore 44 of work piece 42. At the same time, if the work piece 42, which in the arrangement shown comprises the body of the hydraulic valve lifter, is pre vented from turning, a very smooth, 'hard'and truly cylindrical surface will be provided on the bore 44 thereof. Rollers 18 are, of course, driven with spindle 12 by reason of the drive provided by guide pins 20. It will be appreciated, of course, that best results are obtained by first forming the bore 44 with a very smooth and accurately dimensioned surface. If, after the bore is formed in this manner, such as by boring, it is telescoped over the rollers 18 as illustrated in Fig. 2' and the spindle 12 rotated and subjected to pressure sufficient to expand millionths of an inch, a mirrorlike hardened surface will be formed on the bore 44 of the work piece 42. 'The'bore 44 will thereafter be admirably suited for use as a cylinder in which a piston of the hydraulic valve lifter may opcrate.

The means'employed for rotating spindle 12 and for may take several forms. In the embodiment illustrated 'in Fig. 1, these means are in the form of a base 48 on which is supported a rather large cylinder 50. At one end, cylinder 50 is provided with a suitable fitting 52 for connecting the cylinder with a source of air under pressure; and from the opposite end of the cylinder, a plunger 54 projects. Plunger 54 is connected with a piston 56 that operates withincylinder 50. At its free end, plunger54 is fashioned with a hub 56 provided with a bore 58; Within bore 58, there is pressfitted the outer race of a bearing 60. The inner race of bearing -60has press fitted therein a piston member 62. Piston 62 is arranged to slide axially within the bore 64 of a cylinder 66. Cylinder 66 is supported for rotation in a bearing block 68 by ball bearings 70 and 72. Cylinder 66 has keyed thereon a pulley 74 having a belt drive 76 with a motor, not illustrated. A clamping nut 78 is'employed for clampingpulley 74 on cylinder 66. Disc 78 on piston 62 is slidably engaged with pins 84) on pulley 74 so that the piston 62 rotates in bearing 60 with cylinder 66 and is adapted to move axially relative thereto. Hub 56 on plunger 54 is prevented from rotating by means of a pin 82 on the hub which engages in an axially extending groove 84 in base 48. Piston 62 is normally biased in a direction out of cylinder 66 by a compression spring 86.

An oil reservoir 88 is mounted on hub 56, and the hub 56 has a passageway 90 therein which connects with reservoir 83 and with an oil chamber 92 in the hub. Piston 62 has an axial bore 94 extending therein and communicating at its rear end with oil chamber 92. Chamber 92 is sealed around piston 62 by an oil seal 96. At its front end, the axial bore 94 in piston 62 communicates with the der 66 connects bore 64 with the bore 46 of the spindle 12.

When it is desired to finish the bore of a work piece such as shown at '42,-the work piece is slipped over the end of the expanding arbor 10 as shown in Fig. 2. The

motor drive with which the belt 76 is connected is then operated so as to rotate the,.arbor. Thereafter, air under pressure is admitted to cylinder 50 through fitting 52 to advance the piston 56 axially therein. At this time, it will be appreciated that the oil level in reservoir 88 will maintain the bore 46, the axial passageway 10,4, bore 64, passageway 94 and oil chamber 92 filled with oil. Since plunger 54 moves forwardly, ball check 98 seats against the outer end of piston 62; and pressure is thus applied .to the oil in the bore 46 of spindle 12. The air pressure applied to cylinder 50 is controlled so as to obtain the desired relatively high pressure within spindle 12 to thus expand the side wall 14 of the spindle and cause the rollers 18 to roll with high pressure contact against the bore 44 of the Work piece.

I claim: v

1. A tool for finishing cylindrical bores comprising an elongate tubular member closed at one end and having means adjacent its other end for connection with a source of fluid under pressure, said member having an outer surface portion of true cylindrical shape which is adapted to be radially expanded when the member is subjected to high internal pressure, a plurality of rollers arranged circumferentially around said cylindrical surface portion and extending axially thereof, said rollers having an axial extent substantially less than said tubular member and terminating at their opposite ends substantially inwardly of the opposite ends of the tubular member and means for supporting said rollers for rolling contact with said cylindrical surface portion.

2. A tool for finishing cylindrical bores comprising a tubular member closed at one end and having means adtubular member to hydraulic pressure, said tubular memher having an outer surface portion of true cylindrical shape, a plurality of cylindrical metal finishing rollers arranged circumferentially around said cylindrical surface portion, said rollers having their opposite ends terminating substantially inwardly of the opposite ends of said tubular member and said cylindrical surface extending axially beyond the opposite ends of said rollers, retainer means on said tubular member for supporting said rollers in rolling contact with said cylindrical surface portion and means for rotating said tubular member about the axis of said cylindrical surface portion.

3. A roller burnishing tool for finishing an internal bore comprising a hollow mandrel having a thin wall of uniform thickness and forming a true circular cylinder, means including a body of liquid for exerting within the mandrel an expanding pressure acting uniformly in all directions, a plurality of burnishing rollers of circular cylindrical form and of a length which is several times their diameter positioned in rolling contact with the outside of the mandrel, cage means acting to constrain the burnishing rollers parallel to the mandrel and adjacent thereto and a stem forming arotary driving connection and having a fluid conduit connecting with the interior of the mandrel.

4. A roller burnishing tool for finishing the interior of a circular bore comprising a set of burnishing rollers which are slender true circular cylinders, a mandrel comprising a thin wall, longer than the rollers and having an uninterrupted truly circular outer surface of uniform diameter throughout its length, a cage for retaining the rollers adjacent the mandrel and in position parallel to the mandrel, means including a body of liquid for exerting radially outward expanding pressure directly and uniformly along the full length and around the full circumjacent its opposite end for subjecting the interior of said i fercnce of the mandrel, a stem for rotating the mandrel and having a conduit connection to the interior of the mandrel.

References Cited in the file of this patent UNITED STATES PATENTS 1,166,040 Burlingham L Dec. 28, 1915 1,373,857 Bosch Apr. 5, 1921 1,472,036 Anderson Oct. 30, 1923 1,619,479 Maupin Mar. 1, 1927 1,627,152 DeWitt May 3, 1927 1,749,982 Nesbitt Mar. 11, 1930 1,917,925 Cogsdill July 11, 1933 2,004,787 Gillette June 11, 1935 2,043,481 Krissiep June 9, 1936 2,170,631 Cogsdill Aug. 22, 1939 2,361,434 Surtees .d Oct. 31, 1944 2,520,126 Collard Aug. 29, 1950 FOREIGN PATENTS 194,575 Great Britain Mar. 15, 1932 494,481 Great Britain Oct. 26, 1938 

